+1 on Stoner's Invisible Glass. Stuff is great and really leaves no streaks. Also, folks often see streaks when cleaning windows and it turns out it is not the cleaner but residues from the paper towels, cloth towels, etc that they are using. Cloth run through a drier with those drier sheets contains a streaking residue, for example. Some paper towels also seem to have some type of an oily substance in them.